Temperature responsive safety valve stems

ABSTRACT

The invention provides a safety valve stem structure for valves having a valve stem and requiring either rotational motion or translational motion to operate the active valve member. A cavity is formed within the stem and a weakened portion is formed in the stem near the cavity. The cavity is filled with a liquid which expands upon exposure to excessive heat and breaks the stem at the weakened portion. After breakage, the expanding liquid, sometimes with a spring assist, closes the valve member.

United States Patent 11 1 1111 3,730,204 Bis sett 1451 May 1, 1973TEMPERATURE RESPONSIVE SAFETY 1.536.019 4/1925 Kelley ..l37/62 X VALVESTEMS 1.878.002 9/1932 Smith ..l37/60 3,022,793 2 1962 Th ..l37 68 [75]Inventor: James S. Bis sett, Bethel Park, Pa. mp

[73] Assignee: Gulf Oil Corporation, Pittsburgh, Primary Examiner-MartinSchwadm" Assistant Examiner-Richard Gerard AttorneyMeyer Neishloss etal. [22] F1led: Sept. 23, 1971 21 Appl. No.: 183,136 [57] ABSTRACT Theinvention provides a safety valve stem structure 52 US. Cl. ..137/68,236/90 251/73 for Valves having a valve stem and requiring either {51]Int. Cl ..F16 k 17/38 rotational motion or translational motion tooperate [58] Field of Search .137/59-62, 67 71 7 the active valvemember. A cavity is formed within the 236 90; 237 80 2 stem and aweakened portion is formed in the stem 51/66 73 near the cavity. Thecavity is filled with a liquid which 56 expands upon exposure toexcessive heat and breaks 1 References Clted the stem at the weakenedportion. After breakage, the UNITED STATES PATEN S expanding liquid,sometimes with a spring assist,

1 th 1 b 753,271 3/1904 Hutton ..137/6O C 0868 8 Va ve mem er 13 Claims,9 Drawing Figures Pat nted May 1, 1973 31,730,204

3 Sheets-Sheet 2 This invention pertains to fluid control valves, andmore particularly the invention concerns structure to be added into suchvalves as a safety precaution so that the valve will automatically closein the event it is exposed to heat which produces a temperature greaterthan some predetermined temperature. The invention has particularutility in chemical plants, petroleum refineries, pipelines andassociated apparatus handling such substances, wherein it is desired toclose off a valve in response to a fire or other source of excessiveheat and temperature. Under the usual circumstances, in the event of afire in such locations, it may be impossible or at least highlydangerous for operators to get near enough to a valve to operate itbecause of the flames, smoke and heat of the fire. The invention may bethough of as a thermostatic valve in that it will respond at or above apredetermined temperature to close the valve.

Virtually all valves for handling fluids which have stems may becharacterized into one or two categories in accordance with the mannerin which the stem is operated to move the active valve member. One ofthese two classes is typified by plug, toggle, or gate valves in whichthe active valving member moves up and down in its opening and closingmotion, i.e., translational motion with respect to the axis of the valvestem. The second type or category of valves is typified by ball valvesin which the active member rotates, and more generally is characterizedby a rotational motion of the active valve member around the axis of thevalve stem.

The invention provides a safety or thermostatic valve closing apparatusof the character described which is positive in operation, virtuallyinstantaneous in closing a valve in response to excessive temperature,insensitive to temperature variations below the actuating temperature,maintenance free in use, simple and economical to manufacture withwell-known techniques and components, inexpensive and easy toincorporate into new and existing valves, and generally efficient, sureand positive in operation and strong and durable to a high degree innormal use.

The present invention differs from conventional emergency valves havinga fusable link or joint or the like in several important aspects.Firstly, valves embodying the present invention include the advantage ofusing th'eusual active valve member for both ordinary and emergencyservice, as opposed to prior devices wherein melting oi'a link orbreaking ofa solid joint activates aspecial emergency only valve member.The importance of this difference is that the possibility of theemergency valving apparatus becoming inopera live, as by corrosion in apivot, or foreign matter wear ing a valve seta, or jamming parts thatshould move in an emergency, or the like, is eliminated in that suchoccurrences would be detected during the normal opera tion ofa valveembodying the invention, and would not be detected in such priordevicesuntil the valve failed to respond to theemergency condition.Secondly, the emergency apparatus of the invention is totally enclosedin the valve stem, whereasin other prior valves a fusable link or aspring loaded member or the like is often external to the valve and thussubject to accidental damage, and requires periodic checking andmaintenance, and the like.

The above and other advantages of the invention will be pointed out orwill become evident in the following detailed description and claims,and in the accompanying drawing also forming a part of the disclosure,in which:

FIG. 1 is an elevational view of a typical translational stem motiontype of valve, with part of the valve A I embodiment of the stem of FIG.1;

FIG. 3 is a cross-sectional elevational view of a second; embodiment ofthe stem of FIG. 1;

FIG. 4 is a view similar to FIG. 'I for the rotational stem motion typesof valves;

FIG. 5 is a cross-sectional elevational view of a first embodiment of astem for use in FIG. 4;

FIGS. 6, 7 and 8 are cross-sectional views taken on lines 6-6, 7--7, and8--8 respectively of FIG. 5; and

FIG. 9 is a view similar to FIG. 5 of a second embodiment of astem'usable in FIG. 4.

Referring now in detail to the drawing, 10 designates a typical valve inwhich the improved stem 12 of the invention may be fitted. The valve 10and stem 12 of FIG. 1 are representative of all the various valveswherein the active member translates, i.e., moves up and down withrespect to the axis of the stem to control the main fluid flow. Suchvalves are very well known and include gate valves and plug valves. Thestem may be moved by a sliding motion, or as shown illustratively, bymeans of threads 14 which mate with suitably formed mating threads inthe neck portion 16 of the valve 10. In an area in which the stem 12 isunobstructed by any other portions of the valve 10 in all positions ofthe stem, the stem is formed with a weakened portion 18, shown typicallyas simply a groove cut into'the material of the stem. The weakenedportion must be located inside the valve body, and also in such aposition that it does not interfere with normal valve operation.Techniques are well known in the valve arts and in other arts, such aswell drilling tools, to form such weakened portions so that the memberwill have a predetermined strength.

A first embodiment 12a and a second embodiment 12b of stems includingthe invention particularly suitable for translational types of closingmotion are shown in FIGS. 2 and 3, respectively. Wherever possible, thesame parts are indicated in these two drawings by the same referencenumerals followed by the appropriate a"orb"suffix.

Valve stem 12a is formed with an elongated central cavity which isfilled with a liquid 20a and in which is positioned a sleeve 22a. Thesleeve 22 of both embodiments is closed at its lower end adjacent theweakened portion 18 for a reason that will appear below. The sleeve 22aonly is formed with a suitable groove to receivesealing means 24 whichmay comprise a spring ring or the like to form a fluid tight sealbetween sealing means 24 and the inside surface of the main cavity inthe stem. Means are provided to assemble the stem of the invention, andto that end mating threads 26 in both embodiments are provided wherebythe invention may be assembled as shown and then used in the valve 10 ina normal manner. The threads 26a and 26b, pinned as at 27 to preventunintentional opening of the cavity,

are exemplary only, welding, friction fit, or similar means could besubstituted.

In selecting a particular liquid for use in these two and in the otherembodiments, it is desirable that the liquid not freeze, not becorrosive to the materials of the valve stem which it contacts, and yetbe sufficiently temperature responsive to expand in response to heat tobreak the weakened portion, in its intended use. Mineral oil or purehydrocarbons are presently preferred, generally.

An important feature of the invention is that it will respond at apredetermined selected temperature to close the valve. Many parameterscan be adjusted to achieve this desideratum; different liquids responddifferently, the dimensions and nature of the weakened portion 18 can beadjusted, the volume within the cavity which is in turn partlycontrolled by the dimensions of the sleeve 22, and/or a predeterminedamount of liquid-free space left in the cavity, will all change theoperating temperature.

In use, in the event the stem is exposed to a temperature greater thanthe preset temperature, then the liquid will expand sufficiently tobreak the stem at the weakened portion 18. It is well known that liquidsexpanding in response to heat produce tremendous forces, for example, afailure of a safety valve in a boiler can cause an explosion of thatboiler, and this despite the fact that steam is a compressible fluid.Another example is where gaskets are broken in liquid pipelines when thefull line is inadvertently sealed at both ends at night and left in thatstate into the next days heat and sunshine. Upon breakage at theweakened portion 18, the liquid 20a remains captured within the sleeve22a because of the seal 24, and the sleeve 22a functions as a piston toclose the active valve member, not shown, connected to the lower end ofthe valve stem below region 18a. The dimension between the weakenedportion 18a and sealing means 24, for any particular valve, when in theFIG. 2 position, is set such that when the valve is fully closed theseal 24 will be at or below weakened portion 18 so that the drivingliquid is released to prevent damage to other parts of the valve, andalso to form a lock between the sealing means 24 and the upper fixedpart of the valve stem. Thus, the valve is automatically both lockedclosed and the driving liquid is allowed to escape. The valve will belocked closed despite the broken edge at 18 because the spring ring 24expands slightly, thus preventing reentry of the sleeve 22 into the stem12.

The FIG. 2 form of the invention is particularly suited to valves which,in use, are either fully open or fully closed only. If the valve werepartly closed, then the predetermined dimension between seal 24 andweakened portion 18a would be greater than that needed to bring theactive valve member to the fully closed position, and it would bepossible, under such conditions of misuse, for the invention to damagesome other parts of the valve.

In FIG. 3, there is shown a second embodiment of the translationalmotion type of stem wherein the seal 24 is omitted, and the sleeve 22bfits loosely in the cavity in the stem 12b. A relatively strongcompression spring 28 is added to the assembly of liquid 20b and loosefitting sleeve 22b. Thus,-when the stem 12b is exposed to the operatingtemperature, the liquid 2022 will rapidly determining the predeterminedoperating temperature for this embodiment 12b, the strength of thespring 28 and the amount of liquid displaced by the spring 28 areimportant factors to be considered. Analytical methods for determiningan operating temperature for all embodiments of the invention are wellknown to those skilled in the art, or alternatively, empirical methodscould be used.

Referring now to FIG. 4, there is shown a valve 30 having a stem 32which carries a stop 34 adapted to cooperate with a fixed stop 36 tolimit the rotation of the stem 32 in the body of valve 30, all in aconventional manner. The valve 30 with the parts 32, 34 and 36 isrepresentative of all the various valves whereinthe active memberrotates, i.e., the opening and closing action is a rotation of the valvestem about its own axis to thereby control the main fluid flow throughthe valve. This second class of valves, as is the case with the FIG. 1type of valve, is very well known to those skilled in the art andincludes, most typically, ball valves and rotating plug valves.Referring to FIGS. 5 and 9, there are shown two embodiments 32a and 32bof the rotational type of valve stem. As before, wherever possible, thesame parts in FIGS. 5 and 9 are indicated by the same reference numeralsfollowed by the appropriate 0 or b suffix.

Valve stem 32a of FIG. 5 has a central cavity which is filled with aliquid 38a. The valve stems 32 are held together by suitable fluid tightmeans, such as pins 41, or welding, or the like, which means serves thesame purpose as the mating threads 26 and pins 27 of FIGS. 2 and 3. Thestems 32 are provided with a weakened portion 42 similar to thestructure 18 of the previous embodiments. Since these rotational typesof valves are typically lubricated through the stem, there is provided apassageway 44, the lower end of which passageway 44 will meet with anannular groove 46, and thence with a passageway 48 which leads to theactive valving member, not shown. At the upper end of the fluid filledcentral chamber, valve stems 32 are formed with a blind opening 50. Oneend of an operating rod 52 is secured into this opening 50 by means of akey 54, see FIG. 6. The connection between the upper end of rod 52 inthe key 54 is such that the rod may not rotate with respect to the key,but is free to slide, axially, with respect to the key. At its lowerend, rod 52 is formed with ,a half-round portion 56, see FIG. 8, whichfits within a three-fourths quadrant blind opening 58. A coil spring hasone end fixed into rod 52 as at 62, see FIG. 7, is then relativelytightly wound around the rod 52, and has its other end secured into thebody of stem 32 as indicated at 64. It should be noted that coil spring60 will be entirely contained in the bottom half of stem 32, i.e., belowweakened portion 42.

In the event the valves 32 should be exposed to a temperature greaterthan the predetermined operating temperature, then fluid 38 will expandsufficiently that the stem will break at portion 42. The energy storedin via rod 52 and key 54 attempts to turn the broken half of the stemabove section 42 in the opposite direction. It should be noted that theaxial length of key 54 is such tive member is in any position other thanthe fully closed position. If the valve should happen'to be closed whenbreakage occurs, the spring will first drive the upper half to the openposition which will cause a motion between the parts 56 and 558 suchthat thereafter the active valve member may not be moved away from thatthe connection between the rod 52 and the key remains operative evenafter the expanding liquid has broken the valve stem and therebypossibly moved the rod axially on the key. The mineral oil or otherexpanding liquid, of course, immediately escapes as soon as breakageoccurs. The rotation of the upper part of the broken valve stem isstopped by the interaction of the normally provided stops 34 and 36 inthe full open position of said upper broken part. Of course, the stops34 and 36 are exemplative only of the many different kinds of studs,stops, or the like travel limiting means normally provided on this typeof valve. The lower broken part of the valve stem, carrying the activevalve member, rotates 90 relative to the upper broken part, now held inthe full open position, and is stopped by interaction of the solidquadrant defining three-quarter opening 58a. Since the closing member,not shown, of the valve is attached to this lower part, the valve is nowclosed.

The FIGS. 5 and 9 structures shown are preferred embodiments, but theessence of the invention can be embodied in further slightly modifiedforms. For example, the function of the sliding key arrangement 54 canalso be incorporated into the halfround end 56 of the rod 52 by simplymaking half-round end 56 sufficiently long and its mating three-quarterquadrant opening 58 sufficiently deep to allow the small amount of axialmotion which occurs upon breakage. In such a case, a solid connectioncould be provided between the rod and the cavity opposite the half-roundend of the rod. Another modification possible is to reverse thestructure as shown in FIGS. 5 and 9, Le, the spring wound quadrant endcould be in the upper end of the stem above weakened portion 42. In allcases, the embodiments 42 of the invention depend for their operation onthe fact that the upper broken half will be easier for the spring 60 toturn than will the lower broken half. It is thought that this conditionwill occur naturally very frequently because the ball or active memberin such valves cooperates with various seals and the like in such valvesto make fluid tight connections which seals and the like produce moredrag on the active member than on the broken upper end of the valvestem. Another possible modification would be to provide quadrantopenings and half-round ends such as 58 and 56 at both ends of thechamber. Such structure would appear to be a redundant extra expense,although such extra parts could be arranged to operate in accordancewith the invention.

However an embodiment is configured, the spring 60 should be so woundthat the external valve stem part is biased to the open position, whichwill correspondingly mean that the active valve member part will bebiased in the opposite closed position. The parts 56 and 58 will be soarranged within the valve stem that the 90 or quarter turn of motionavailable will be used to permit the spring force on the active memberpart of the stem to close the stem if breakage should occur when theacits normally closed position by the spring. If the valve happened tobe in the open position when breakage occurred, then the spring cannotmove the upper half, it being already against its open position stop,but the spring will be able to move the active member from that openposition around to the closed position.

In FIG. 9 there is shown the second embodiment 32b having the addedfeature of a compression spring 66 in the fluid filled chamber, one endof which bears against the top of the cavity, and the other end of whichbears against a washer 68 seated on top of the coil spring 60b. Thestructure 66 and 68 assures separation between the broken halves at theregion 42, and thereby facilitates turning of the parts as describedabove by the energy stored in spring 60b. The spring 66 is such that itdrives the upper half only a short distance, and, if necessary in aparticular embodiment, the travel limiting stops or the like, typifiedat 36, could be lengthened to accommodate this slight motion.

The invention would be fabricated of ordinary materials, all as is clearto those skilled in the art. For example, using a mineral oil or otherhydrocarbon driving liquid, the various springs would most likely bemade from suitably tempered spring steel. The operating rod 52 andsleeves 22 could be made from mild steel. The stems 12 and 32 themselveswould be made from whatever material was alre-adyused in any particularvalve, such as brass or steel.

While the invention has been described in detail above, it is to beunderstood that this detailed description is by way of example only, andthe protection granted is to be limited only within the spirit of theinvention and the scope of the following claims.

I claim:

1. ln a valve having a valve stem which carries an active valve member,the improvement comprising a chamber in said valve stem, an expandablefluid in said chamber substantially filling said chamber, a weakenedportion in said stem in a predetermined relation to said chamber thereinand responsive to expansion of said fluid to break said valve stem atsaid weakened portion, and means in said chamber to move the activevalve member on said valve stem to a closed position after said fluidhas expanded sufficiently to break said valve stem.

2. The combination of claim 1,. said fluid consisting of mineral oil.

3. The combination of claim I, wherein said valve is closed afterbreakage by a translational motion of said active valve member withrespect to the axis of said valve stem.

4. The combination of claim 3, said chamber being of generally elongatedshape, said moving means in said chamber comprising a sleeve locatedwithin said chamber extending substantially coextensive with the lengthof said chamber, sealing means in said sleeve in spaced relation to saidweakened portion, whereby upon breakage of said weakened portion saidsealing means contains said expanding fluid and causes said sleeve toact as a piston to close said active member.

tive valve member with respect to the axis of said valve I stem, andwherein the broken valve stem part carrying the active valve memberrequires more energy to turn than does the other broken valve stem part.

7. The combination of claim 6, said moving means comprising an operatingrod axially traversing said chamber, coil spring means interconnectingsaid rod with a portion of said valve stem to one side of said weakenedportion, and means between the end of said rod carrying said coil springmeans and the associated end of said chamber to permit substantially 90of rotational motion therebetween.

8. The combination of claim 7, and means to permit limited slidingmotion between at least one end of said rod and the associated portionof said valve stem at the associated at least one end of said chamber.

9; The combination of claim 8, said means to permit said limited slidingmotion comprising a key and slot connection between the end of said rodopposite said coil spring means and the associated portion of said valvestem.

10. The combination of claim 7, said 90 motion permitting meanscomprising a three-quarter quadrant blind opening formed in said end ofsaid chamber and a half-round end formed on said end of said rod andfitted into said blind opening.

11. The combination of claim 7, wherein said coil spring means and said90 motion permitting means are located in said chamber on the activevalve member side of said weakened portion.

12. The combination of claim 7, and compression spring means in saidchamber having one end bearing against an end of said chamber and theother end operatively cooperable with said coil spring means, wherebyupon breakage of said stem at said weakened portion said compressionspring will separate the broken parts of said stem at said weakenedportion to thereby facilitate rotation of said broken parts with respectto each other under the influence of said coil spring means.

13. The combination of claim 12, and a washer interposed between saidcoil spring means and said compression spring.

1. In a valve having a valve stem which carries an active valve member,the improvement comprising a chamber in said valve stem, an expandablefluid in said chamber substantially filling said chamber, a weakenedportion in said stem in a predetermined relation to said chamber thereinand responsive to expansion of said fluid to break said valve stem atsaid weakened portion, and means in said chamber to move the activevalve member on said valve stem to a closed position after said fluidhas expanded sufficiently to break said valve stem.
 2. The combinationof claim 1, said fluid consisting of mineral oil.
 3. The combination ofclaim 1, wherein said valve is closed after breakage by a translationalmotion of said active valve member with respect to the axis of saidvalve stem.
 4. The combination of claim 3, said chamber being ofgenerally elongated shape, said moving means in said chamber comprisinga sleeve located within said chamber extending substantially coextensivewith the length of said chamber, sealing means in said sleeve in spacedrelation to said weakened portion, whereby upon breakage of saidweakened portion said sealing means contains said expanding fluid andcauses said sleeve to act as a piston to close said active member. 5.The combination of claim 3, said chamber being of generally elongatedshape, said moving means in said chamber comprising a sleeve locatedwithin said chamber and loosely fitted therein and compression springmeans within said sleeve within said chamber, whereby said expandingfluid will break said weakened portion to release said compressionspring means to thereby close said active member.
 6. The combination ofclaim 1, wherein said valve is closed after breakage by a rotationalmotion of said active valve member with respect to the axis of saidvalve stem, and wherein the broken valve stem part carrying the activevalve member requires more energy to turn than does the other brokenvalve stem part.
 7. The combination of claim 6, said moving meanscomprising an operating rod axially traversing said chamber, coil springmeans interconnecting said rod with a portion of said valve stem to oneside of said weakened portion, and means between the end of said rodcarrying said coil spring means and the associated end of said chamberto permit substantially 90* of rotational motion therebetween.
 8. Thecombination of claim 7, and means to permit limited sliding motionbetween at least one end of said rod and the associated portion of saidvalve stem at the associated at least one end of said chamber.
 9. Thecombination of claim 8, said means to permit said limited sliding motioncomprising a key and slot connection between the end of said rodopposite said coil spring means and the associated portion of said valvestem.
 10. The combination of claim 7, said 90* motion permitting meanscomprising a three-quarter quadrant blind opening formed in said end ofsaid chamber and a half-round end formed on said end of said rod andfitted into said blind opening.
 11. The combination of claim 7, whereinsaid coil spring means and said 90* motion permitting means are locatedin said chamber on the active valve member side of said weakenedportion.
 12. The combination of claim 7, and compression spring means insaid chamber having one end bearing against an end of said chamber andthe other end operatively cooperable with said coil spring means,whereby upon breakage of said stem at said weakened portion saidcompression spring will separate the broken parts of said stem at saidweakened portion to thereby facilitate rotation of said broken partswith respect to each other under the influence of said coil springmeans.
 13. The combination of claim 12, and a washer interposed betweensaid coil spring means and said compression spring.